. "Signal Butte, or site 25Sf1, is an archaeological site near Gering, Nebraska.It was declared a National Historic Landmark in 1961.At its designation, it was stated:Discovered in 1931, this is the first site of the middle prehistoric period in the central and northern Plains to be excavated by archeologists."@en . "66000452" . . "1966-10-15Z"^^ . . "Signal Butte"@en .